Camera Tamper Detection

ABSTRACT

A security system ( 20 ) includes at least one camera ( 22 ) that provides a reference image regarding an area within a field of vision ( 24 ) of the camera ( 22 ). A controller ( 30 ) determines whether a difference between at least a portion of a test image obtained by the camera ( 22 ) and a corresponding portion of the reference image indicates tampering with the camera. Disclosed examples detect a variety of tampering conditions and provide an indication of camera tampering so that corrective or preventative measures may be taken.

BACKGROUND OF THE INVENTION

This invention generally relates to security systems. More particularly,this invention relates to security systems including cameras.

Security systems are well known and in widespread use. Many such systemsinclude cameras for providing visible images of selected objects orareas in or around buildings, for example. Some known security systemsinclude providing a live feed to one or more display devices to allow anindividual to observe current conditions within a field of vision of thecamera. Other systems include cameras that record images over time sothose images can be recalled and used for investigations of criminal orunauthorized activity.

It is possible for someone to attempt to defeat the security system orat least to hinder the functionality of the security system by tamperingwith one or more cameras. One technique includes physically moving thecamera to change its field of vision so that the camera is not able tomonitor a particular area or to provide an image of a particular object,for example. Other techniques include placing a substance on the lens ofthe camera such as paint or grease, for example. Such a substancerenders the camera out of focus or unable to provide a discernableimage. Another technique is to place an object in front of the camera orat least over the lens so that the field of vision of the camera iscompletely blocked.

For security systems that provide a live feed to a monitor or displayobserved by an individual, such tampering may be readily evident to theindividual responsible for watching the displays such that appropriateaction may be taken. For systems that record images without providing alive feed, for example, it is not possible to detect such cameratampering under many circumstances. Additionally, even when a live feedis provided, the responsible individual may not be able to discernsubtle changes caused by particular types of tampering with a camera.

There is a need for an arrangement that can detect when a camera hasbeen tampered with because that typically is an indication thatunauthorized or illegal activity is occurring or may be occurring in thenear future. This invention addresses that need.

SUMMARY OF THE INVENTION

This invention provides the ability to automatically detect when acamera has been tampered with so that appropriate corrective orpreventive action may be taken. This invention provides an automatedcamera tampering detection arrangement that has a wide variety of uses.

An exemplary disclosed security system includes at least one camera thatprovides an image. A controller determines whether a difference betweenat least a portion of a test image from the camera and a correspondingportion of a reference image from the camera indicates tampering withthe camera.

In one example, the controller determines whether the difference betweenthe corresponding portions of the test image and the reference image isassociated with some movement within a field of vision of the camera. Inone example, information from a motion detector provides an indicationwhether movement within the field of vision of the camera is responsiblefor the difference between the test image and the reference image. Inanother example, a plurality of successive test images are acquired anddifferences between the test images are used to provide an indication ofmovement within the field of vision of the camera.

One example includes providing a signal or indication of detected cameratampering so that an appropriate response can be made.

The disclosed example embodiments provide the ability to detect cameratampering, which may be associated with ongoing unauthorized or illegalactivity. Additionally, disclosed examples provide the ability to detectvarious types of camera tampering that may be an indication of futureplanned illegal activity, which provides the advantage of being able totake action to prevent such activity before it occurs.

The various features and advantages of this invention will becomeapparent to those skilled in the art from the following detaileddescription of a preferred embodiment. The drawings that accompany thedetailed description can be briefly described as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates selected portions of a security systemdesigned according to an example embodiment of this invention.

FIG. 2 is a flowchart diagram summarizing one example camera tamperingdetection technique.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 schematically shows selected portions of a security system 20. Acamera 22 has a field of vision 24 arranged to provide visibleinformation regarding at least one object or an area within a building.In the illustration, an entryway 26 is within the field of vision 24 ofthe camera.

A controller 30 obtains information from the camera 22 using knowndigital signal and digital image processing techniques. In this example,the controller 30 has access to a database 32 of reference image data.At least one reference image from the camera 22 is stored in thedatabase 32. The reference image provides a baseline of data regardinghow the area or objects within the field of vision 24 of the camera 22should appear when the camera is functioning properly and appropriatelyarranged to have the desired field of vision. In one example, at leastone reference image is obtained when the camera is initially set into adesired orientation, properly focused and in a known operatingcondition.

The controller 30 periodically obtains information regarding test imagesfrom the camera 22. An image processing portion 34 of the controller 30in one example uses known digital image processing techniques to obtaininformation regarding the test image or test images. A processingportion 36 of the controller 30 uses known techniques to determinewhether there is a difference between at least a portion of a test imageand a corresponding portion of a corresponding reference image withinthe database 32. When there is such a difference, that may indicate thatthe camera 22 has been tampered with because the portion of the testimage does not match up with the corresponding portion of referenceimage.

Some examples utilize a selected portion of images for comparison todetermine whether there is a difference indicative of camera tampering.Other examples use an entire image. This description refers todifferences between images but that is intended to apply to onlycorresponding portions of such images, also. Given this description,those skilled in the art will be able to select appropriate portions ofimages to meet their particular needs. One example includes selecting aportion of the image that is unlikely to be altered by movement throughthe corresponding portion of the field of vision 24 or by changing lightconditions.

Of course, it is possible for an individual or an object moving throughthe field of vision 24 of the camera 22 to cause the test image to bedifferent than the reference image. The illustrated example includes theability to determine whether motion within the field of vision 24 of thecamera 22 is responsible for a difference between a test image and thereference image. A motion determining portion 38 in one example utilizesinformation regarding more than one test image taken successively withina selected period of time (e.g., five seconds) to determine whetherthere are differences between the test images, which would indicatemovement of an individual or object through the field of vision 24 ofthe camera 22. For example, if an individual were walking through theentranceway 26 at the time that the test image is obtained, thatindividual will be in different positions within a plurality of testimages taken successively over a short period of time. Such differencesbetween the test images, determined using known digital image processingtechniques in one example, provides an indication that something movingwithin the field of vision 24 of the camera 22 is responsible for thedifference between the test image and the reference image. Under suchcircumstances, the controller 30 in one example determines that there isno conclusive evidence of camera tampering.

In the event that such motion is associated with camera tampering, alater-acquired test image will reveal a difference indicating tampering.

In another example, a known motion detector device 40 such as apyroelectric sensor detects motion in an area corresponding to the fieldof vision 24. Appropriate signals from the motion detector 40 are usedin one example by the motion determining portion 38 and the processingportion 36 for discerning whether a difference between a test image andthe reference image is the result of potential camera tampering orcaused by an individual or object moving through the field of vision 24at the time that the test image was obtained.

FIG. 2 includes a flowchart diagram 50 that summarizes one exampleapproach for determining whether the camera 22 has been tampered with.At 52, a test image is acquired from the camera 22. The processingportion 36 determines whether the appropriate portion of the test imagecorresponds to the corresponding portion of the reference image at 54.If there is no difference between the test image and the referenceimage, the next test image will be acquired at 52. The time betweenacquiring test images may be selected to meet the needs of a particularsituation.

Assuming that the test image and the reference image are somehowdifferent, the example process of FIG. 2 continues at 56 where thecontroller 30 determines whether motion within the field of vision 24 isresponsible for the difference between the images. Using informationfrom a motion detector in one example allows for ruling out a differencebetween the test image and the reference image that is caused bysomething moving within the field of vision 24.

The example of FIG. 2 includes acquiring at least one additional testimage at 58. A determination is made at 60 whether the additional testimage is the same as the earlier test image. A difference between theadditional test image and the earlier test image indicates, at leastunder some circumstances, that something has moved within the field ofvision 24 during a time associated with acquiring the test images. Inthe illustrated example, if there is a difference between the additionaltest image and the earlier test image, the controller 30 determines thatmotion within the field of vision 24 is responsible for the differencebetween the test image and the reference image. In the event that thetest images are the same, the illustrated example, that is considered anindication that nothing is moving within the field of vision 24 and thatthe camera has been tampered with.

One example includes obtaining a plurality of test images all within aselected period of time each time that test image information isdesired. In such an example, the controller 30 determines whether thereis a difference between at least one of the test images and thereference image. If there is such a difference, the controller 30 thencompares at least two of the test images to determine whether thedifference between the one test image and the reference imagecorresponds to movement within the field of vision 24. In this example,if there is no difference between the one test image and the referenceimage, the other test images need not be used for any particularprocessing at this time.

At 62, a report of the camera tamper is made to an appropriate responseunit 64 (FIG. 1), so that corrective or preventive action may be taken.In one example, a tamper alarm indication provides information thatthere may be ongoing illegal or unauthorized activity and an appropriateresponse can be made. In another example, the camera tamper indicationprovides information for a service technician to visit the site of thecamera to make any corrections, adjustments or repairs that may benecessary to ensure that the camera continues providing informationregarding the desired area.

The example of FIG. 2 includes an ability to provide an indication of anexpected type of camera tampering. In this example, at 66, theprocessing portion 36 analyzes the difference between the test image andthe reference image and at least estimates a type of camera tamperingthat may have occurred. One example includes using known digital imageprocessing techniques to analyze the difference between the images. Oncean appropriate determination has been made or at least approximated, at68, that determination is reported at 62 to the response unit 64. In oneexample, the reported, expected type of tampering can be used todetermine an appropriate response.

The types of tampering that can be determined in one example includethat the camera has been moved, the camera has been adjusted (e.g.,placed out of focus), something is blocking at least a portion of thefield of view of the camera or a substance such as grease or paint hasbeen placed on a lens of the camera. Discerning between these differenttypes of tampering in one example is based upon a determination whetherthe test image provides any information, distorted information ordifferent information from the reference image.

When the test image does not provide any information that is associatedwith an indication that the camera has been turned off, blocked orcovered, for example. When the test image provides different informationfrom the reference image, that is associated with an indication that thecamera has been moved. When the test image provides distortedinformation that is associated with an indication that the camera hasbeen adjusted out of focus. When the amount of light associated with thetest image is significantly different than that associated with thereference image, that is associated with an indication that a substancehas been placed on the lens of the camera.

One example includes storing a plurality of reference images, eachcorresponding to a different condition that is likely to have an effecton the content of the test image. In one example, reference images fordifferent times of day are taken and stored within the database 32.Different times of day may be associated with different lightingconditions or different shadowing effects, for example. Accordingly, oneexample includes obtaining different reference images for such differentconditions. In one example, the controller 30 determines the time of dayassociated with a test image and selects an appropriate reference imagefor malting the determination whether the camera 22 has been tamperedwith. In another example, the controller 30 uses information regardingexpected or actual lighting conditions for selecting the appropriatereference image for making the determination regarding potential cameratampering.

It should be noted that the various portions of the example controller30 are schematically shown for discussion purposes. Some of thediscussed functions may be accomplished using more controllers.Similarly, some of the described portions may be integrated. Thoseskilled in the art who have the benefit of this description will realizehow to use one or more processors to accomplish the results provided bythe example controller 30. Given this description, those skilled in theart will be able to select appropriate software, hardware, processors orcombinations of them to realize a controller that operates consistentwith the example controller 30 from this description.

As can be appreciated, the disclosed examples provide an automatedsystem and method for determining whether a security system camera hasbeen tampered with. The disclosed examples provide the ability for asecurity system to have an enhanced capability of recognizing ongoingillegal or unauthorized activity or conditions that may indicate thatsuch activity is planned. In either event, the disclosed examples allowa security system operator to ensure that the security system iscontinually providing the desired amount of information for establishingthe desired level of security.

The preceding description is exemplary rather than limiting in nature.Variations and modifications to the disclosed examples may becomeapparent to those skilled in the art that do not necessarily depart fromthe essence of this invention. The scope of legal protection given tothis invention can only be determined by studying the following claims.

1-20. (canceled)
 21. A method of operating a security system having atleast one camera, comprising: determining whether a difference betweenat least a portion of a test image from the camera and a correspondingportion of a reference image from the camera is associated with somemovement within a field of vision of the camera; and determining whetherthe difference between the portion of the test image and the referenceimage indicates tampering with the camera.
 22. The method of claim 21,comprising detecting motion in an area corresponding to the field ofvision of the camera approximately when obtaining the test image. 23.The method of claim 21, comprising obtaining at least one subsequenttest image and determining whether there is a second difference betweenat least corresponding portions of the test image and the subsequenttest image.
 24. The method of claim 23, comprising obtaining a pluralityof test images within a selected time and using at least two of theplurality of test images for determining whether the second differenceexists if there is a difference between the portions of the referenceimage and the test image.
 25. The method of claim 21, comprisingproviding an indication of an alert condition when the determineddifference indicates tampering with the camera.
 26. The method of claim21, comprising determining whether the tampering is at least one ofmoving the camera, adjusting the camera, blocking the camera, placing asubstance on a lens of the camera, placing an object in front of thecamera or turning off the camera.
 27. A method of operating a securitysystem having at least one camera, comprising obtaining a plurality ofreference images from the camera corresponding to a plurality ofdifferent conditions; determining which of the conditions exists whenobtaining a test image from the camera; selecting one of the referenceimages corresponding to the condition existing when obtaining the testimage; and determining whether a difference between at least a portionof the test image and a corresponding portion of the selected referenceimage indicates tampering with the camera.
 28. The method of claim 27,wherein the conditions comprise times of day and the method includesdetermining a time of day associated with the test image.
 29. The methodof claim 27, wherein the conditions comprise lighting conditions and themethod includes determining an expected one of the lighting conditionsassociated with the test image.
 30. The method of claim 27, comprisingproviding an indication of an alert condition when the determineddifference indicates tampering with the camera.
 31. The method of claim27, comprising determining whether the tampering is at least one ofmoving the camera, adjusting the camera, blocking the camera, placing asubstance on a lens of the camera, placing an object in front of thecamera or turning off the camera.
 32. A security system, comprising: atleast one camera that provides an image; and a controller thatdetermines whether a difference between at least a portion of a testimage from the camera and a corresponding portion of a reference imagefrom the camera is associated with some movement within a field ofvision of the camera and determines whether the difference between theportion of the test image and the reference image indicates tamperingwith the camera.
 33. The system of claim 32, comprising at least onemotion detector for detecting motion in an area corresponding to thefield of vision of the camera and wherein the motion detector providesan indication of motion to the controller responsive to detecting motionin the area.
 34. The system of claim 32, wherein the controller uses atleast one subsequent test image from the camera and determines whetherthere is a second difference between at least corresponding portions ofthe test image and the subsequent test image.
 35. The system of claim34, wherein the camera provides a plurality of test images within aselected time and the controller uses at least two of the plurality oftest images for determining whether the second difference exists ifthere is a difference between the portions of the reference image andthe test image.
 36. The system of claim 32, wherein the controllerprovides an indication of an alert condition when the controllerdetermines that the difference indicates tampering with the camera. 37.The system of claim 32, wherein the controller determines whether thetampering is at least one of moving the camera, adjusting the camera,blocking at least a portion of a field of view of the camera, placing asubstance on a lens of the camera or turning off the camera.
 38. Asecurity system, comprising: at least one camera that provides an image;a controller that determines whether a difference between at least aportion of a test image from the camera and a corresponding portion of areference image from the camera indicates tampering with the camera; anda memory containing a plurality of reference images associated with aplurality of different conditions and wherein the controller selects anappropriate one of the plurality of reference images corresponding to acondition associated with the test image.
 39. The system of claim 38,wherein the conditions comprise times of day and the controllerdetermines a time of day associated with the test image.
 40. The systemof claim 38, wherein the conditions comprise lighting conditions and thecontroller determines an expected one of the lighting conditionsassociated with the test image.
 41. The system of claim 38, wherein thecontroller provides an indication of an alert condition when thecontroller determines that the difference indicates tampering with thecamera.
 42. The system of claim 38, wherein the controller determineswhether the tampering is at least one of moving the camera, adjustingthe camera, blocking at least a portion of a field of view of thecamera, placing a substance on a lens of the camera or turning off thecamera.